Kinetic Study in Intermacromolecular End-to-End Photodimerization of α-Anthrylpolystyrene in Dilute Solution

Abstract

The rates of an intermolecular photodimerization reaction of 9-methylanthracene (model reaction) and an anthryl group attached to the polymer chain end in various solvents were evaluated from the change in fluorescent or UV absorption intensities of the anthryl group during continuous irradiation by a high-pressure mercury lamp. The assumption that dimerization is diffusion-controlled reaction was confirmed by the fact that the rate constants for photodimerization of 9-methylanthracene were inversely proportional to the solvent viscosity in various mixed hexane-pentadecane solutions. The rates of intermacromolecular photodimerization for α-anthrylpolystyrene with different degrees of polymerization, N, under the conditions of a very dilute solution in benzene (good solvent) were substantially independent of the degree of polymerization over the range of N from about 40 to 550.